1. Technical Field
The present invention generally relates to semiconductor devices and methods of fabricating the semiconductor devices. More particularly, the present invention relates to semiconductor devices and methods of fabricating nickel-free silicide for contact metallization.
2. Background Information
Silicide processes have been widely used to form silicide contacts on the gate and source/drain during the semiconductor device fabrication processing to improve the performance of the semiconductor device. The silicide layer improves the operational speed of the semiconductor device by reducing the contact resistance between the metal contact and source and drain.
More recently, nickel monosilicide (NiSi) has been employed as the silicide material of choice, because of the several advantages associated with it, such as, for example, low resistance (10.5-18 μΩcm) and low formation temperature (350° C.). However, nickel silicide is sensitive to oxygen contamination from the ambient air and from residual interfacial contaminants such as native oxides. Such contamination can lead to rough and/or insulating interfaces causing high contact resistance in the device. The diffusion characteristics of nickel into underlying silicon (Si), silicon germanium (SiGe) and germanium (Ge) substrates can create issues such as, piping/spiking defects during the silicidation process, which leads to leakage of current into the channel as well as the junction regions, resulting in degradation in device performance.
Hence, there exists a need to develop silicidation processes lacking nickel for improving the semiconductor device performance in scaled-down technologies.